This invention relates to an air bag restraint system for a motor vehicle and in particular to an improved design of such device particularly adapted for a passenger-side application for frontal impact protection having improved assembly and design features.
Inflatable restraint systems are now in widespread use in motor vehicles as a passive occupant restraint device for impact protection. The air bag restraint system inflates in response to an electrical signal from one or more crash sensors mounted to the motor vehicle and provides energy absorption for the motor vehicle occupants in the event of a frontal crash. Air bag restraint systems are presently used for front seat occupants and can be broadly categorized in two groups; those for driver's-side application and those for passenger-side application. The driver's-side module is typically mounted to the motor vehicle steering wheel hub. The passenger-side module is generally mounted to the vehicle's instrument panel and provides protection for one or two front seat passengers.
Passenger-side air bag systems are in widespread use and provide excellent impact protection. Designers of such devices are, however, continuing to strive to improve their performance, quality, and reduce their costs through improvements in assembly operations and design. In a typical design of a passenger-side module, a tub shaped metal reaction housing typically made of metal in a tubular shape is provided within which an elongated cylindrical inflator is mounted. The reaction housing has an open side which forms a perimeter flange. The flexible folded air bag typically formed of woven polyester or nylon material is mounted to the reaction housing around the perimeter flange. Some designs utilize four separate steel plates and fasteners to anchor the air bag to the rectangular reaction housing flange. This design requires intricate and expensive assembly fixturing to hold the plates and bag in place while rivets or screws are installed. This usually creates a limitation in the production process. In some current production modules, fourteen or more separate rivets or other fasteners are used to attached the bag in place to the reaction housing. Other designs implement steel stampings sewn into the mouth of the air bag which are held in place while screws or rivets are installed to anchor the air bag to the reaction housing. This design is perhaps an improvement but still requires many discrete fasteners.
As an improvement to the above referenced currently known designs, other techniques for simplified mounting of an air bag and inflator to a reaction housing have been proposed. These designs often incorporate an inflator which is placed within the enclosed volume of the air bag causing the air bag to be inflated from within as opposed to through an inflation opening. Often the air bag is gathered along a seam which is affixed to the reaction housing by mechanical fasteners. For example, according to U.S. Pat. Nos. 4,153,273; 4,964,654; 4,944,527 and 5,062,664, a separate cylindrical sleeve is provided with mounting studs which receive the cylindrical inflator. This assembly is placed inside the bag through an opening and a pair of flaps of the air bag are overlapped to close the opening. In each of the designs described by the above referenced patents, a separate component apart from the inflator is provided for housing and mounting the inflator. In addition, they require a number of specialized threaded fasteners for retaining the inflator in position.
In accordance with this invention an improved approach toward attaching an air bag and inflator to a reaction housing is provided. An attachment member is used which may be made of a molded plastic material can be sewn directly to the air bag fabric. One such attachment member features protruding studs which pass through holes in a pair of air bag flaps, seaming together the flaps to enclose the bag. These protruding studs fit within apertures of the reaction housing and prevent the flaps of the bag from separating in response to deployment forces and further maintain the bag attached to the reaction housing. A simplified inflator mounting approach is employed for fastening the inflator to the reaction housing. Once fastened in position, the inflator traps the attachment member such that the studs cannot be withdrawn from the reaction housing apertures in the event of air bag deployment.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.